In recent years significant progress has been made in the use of thermography as a non-invasive screening technique for the early detection of cancer and as a diagnostic tool for visualizing and locating areas of the human body wherein there is some malady.
Thermographic techniques can be divided into three general types: contact thermography where temperature variations are measured by direct contact with the skin surface, long wave infra-red thermography or electronic thermography, wherein infra-red radiation radiated from the skin surface is detected, for example, using a solid state crystal receiver for wavelengths in the range of (approximately) 8 to 15 microns, and wherein the surface is scanned and an image normally reproduced electronically; and absorption thermography wherein the skin is irradiated with short wave infrared radiation and a photographic of the energy reflected from the body taken on infra-red film.
Thermographic techniques dealing with infra-red radiation which is reflected from the body being scanned, are not generally used clinically although variations thereof (including techniques using micro-waves rather than infra-red radiation) are presently being studied. Infra-red (or other similar radiation) is directed against the skin surface, and may penetrate the skin a short distance. Energy not absorbed is radiated and the resulting image has some diagnostic uses.
The present invention is concerned with contact thermography wherein heat generated by the body's processes is measured directly. Long wave infra-red or electronic thermography measures heat generated by the same phenomenon except that measurement is made by measuring infra-red radiation above the skin rather than by direct contact with the skin.
Long wave infra-red or electronic thermography has been found very useful as a diagnostic tool and much recent work has been done in studying lower back injuries. The results of applying thermographic techniques to detect lower back injuries, and especially to Lumbar Disc Disease, have been found to be comprable to more standard techniques. However, as an initial diagnostic tool, these thermographic methods have the overwhelming advantage of being noninvasive and easily accomplished. See, for example, "Thermography of the Spine," Applied Radiology, September-October 1976 (pages 103-105); and "Peripheral Thermographic Manifestations of Lumbar-Disc Disease," Applied Radiology, September-October 1978; where thermographic techniques employing long wave infra-red thermography are described.
Although long wave infra-red or electronic thermography shows great potential for diagnostic purposes, the equipment necessary to make electronic thermographs is relatively expensive, with an average price of about fifty thousand dollars. The device includes an appropriate receiver or sensor for infra-red radiation in the 8-15 micron region, and usually uses moving mirrors to collect radiation over the area of the body to be scanned. The response of the detector is then reproduced as an electronic image analogously to the manner in which an image is prepared on a television set. This may be photographed to provide a permanent record.
In general, thermography is potentially a very powerful diagnostic tool. Temperature rises in various parts of the body can result from any malady against which the body's immune system mounts an attack, including nerve irritation, infection, bone misalignment, so-called auto-immune ailments or other perceived irritations within the body. For example, cancerous cells (Neoplasms) generate heat due to rapid or excessive metabolic processes characteristic thereof. Blood flow variations, due to a blocked or partially blocked artery, or to nerve irritations such as can be caused by Spinal column disc misalignment or cracking--or any other cause, will result in asymetric temperature variation useful as an indication of possible problems. By correlating asymetric temperature variations with previous medical history, and other medical/physiological knowledge, a skilled practitioner is able to diagnose--or at least be aware of probable ailments. This is not unlike the well-known use of general body temperature as an indication of an infection--although thermography is more specific. Although the magnitude of the temperature variation, often only 0.1-0.3 degrees Farenheit, depends on may factors, such temperature variations can often be detected by measurement of temperature variations in the skin.
An important development which has made contact thermography a practical reality was the development of liquid crystals and of methods for supporting liquid crystals on various substrates to form temperature responsive sheets of material. Such materials are described, for example, in U.S. Pat. Nos. 3,619,254 and 3,969,264. These patents disclose methods for preparing suitable liquid crystals carrying films having various substrates. These materials can be used to accomplish similar diagnosis as that formally attainable using expensive thermographic equipment, as outlined above.
The main problem encountered with contact thermographic methods was to ensure good and even contact between the liquid crystals and the skin. Early techniques involved painting a black undercoat directly onto the patient's skin and applying liquid crystals directly to the undercoating. This ensured good and even contact with the skin but was a rather burdensome method involving some discomfort and inconvenience to the patient.
Liquid crystal carrying plates were an improvement over the direct coating method with respect to patient comfort, but were difficult to use with respect to obtaining good and even contact with the skin. This was especially true where highly contoured portions of the skin were being scanned, such as the female breast or highly curved portions of the body frame.
U.S. Pat. Nos. 3,830,224 and 3,847,139 were drawn to devices which endeavored to obtain close contact with the female breast by supporting liquid crystals on a suitable garment such as a brassiere-like device. These were an improvement over the relatively inflexible plates earlier used, but still had limited coverage and were confined to the specific tissue for which they were designed. In addition, the brassiere shape was found to deform the breasts at various points so that, depending on the size and the shape of the woman's breast, some portions of the brassiere did not come into contact with the breast at all while other portions contacted the breasts to such an extent as to deform the breasts thereby producing artifacts or distorted thermograms.
The invention disclosed in U.S. Pat. No. 4,135,497, provides a device which is a simple and effective solution to the problem of close conformity to the tissues, while avoiding the disadvantages of the earlier liquid crystal devices. Basically, the device of U.S. Pat. No. 4,135,497, includes a liquid crystal carrying elastic flexible film which is applied over the complete skin area where the tissues are to be thermographed. Air enclosed between the skin and the film is evacuated through a special valve and spacer arrangement, thereby to cause the liquid crystal carrying film to conform closely to the shape and contour of the skin. The color pattern which forms on the film can then be directly observed and photographed.
Although the device of U.S. Pat. No. 4,135,497 provides close and complete contact with the skin surface which is to be scanned, the method of using the device requires first that the area to be scanned be wrapped with the temperature responsive film; then spacers must be inserted; and evacuation equipment applied to conform the film to the body. In addition, the film must be generally designed for use over the portion of the body intended to be scanned and only has limited use over other tissue portions. Thus the same device may not be useable over other portions of the body.
The present invention incorporates the advantages of the device of U.S. Pat. No. 4,135,497, without the need for special techniques to ensure smooth conformity to the body, and is generally applicable to all portions of the body. The present invention device may even more portable and inexpensive than is the device of U.S. Pat. No. 4,135,497.